<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    let obj = {};
    console.log(obj); // 有些时候，会看到这个结果 { name: 'zs', age: 20 }

    obj.name = 'zs';
    obj.age = 20;
  </script>
</body>

</html>